Device for heat treatment of strips and the like

ABSTRACT

The invention relates to a method and apparatus for heat sealing dyes in running lengths of synthetic material by traversing it into a tubular passageway of a heated receptacle and then advancing it longitudinally over a curvilinear surface area of the upper wall of said passageway. Receptacles which have plural passageways are also comtemplated for traversing the synthetic material in reverse directions to heat treat both sides thereof.

United States Patent Sohr et a1. Oct. 30, 1973 [54] DEVICE FOR HEAT TREATMENT OF 2,115,630 4/1938 Gruber-Rehenburg et al.. 68/D1G. 1 STRIPS N THE LIKE 2,203,678 6/1940 Dursteler 68/D1G. 1

2,424,857v 7/1947 75 Inventors: Hans U|rich 50hr, NaSSaUILaI-mg 2,468,081 4/1949 Koster 68/D1G. l

Reinhard Leo, Dietzenbach; gofgang g i fi i g i Primary Examiner-William I. Price ermann O 0 pren mgen AttorneyEdwin E. Greigg all of Germany [73 I Assignee: Hans-Ulrich Sohr, Nassau Lahn,

Germany 57 ABSTRACT [22] Filed: Apr. 5, 1972 The invention relates to a method and apparatus for [21] Appl' 241354 heat sealing dyes in running lengths of synthetic material by traversing it into a tubular passageway of a [52] U.S. Cl 8/149.l, 8/1492, 8/1512, heated receptacle and the" advancing it longitudinally 68/5 68/DIG' I over a curvilinear surface area of the upper wall of I Cl. "I HY... said p g y Receptacles plural [58] Field of Search 8/151,151.2, 149.1, Sageways are also comtemplated for traversing the 68/DIG' 5 5 E synthetic material in reverse directions to heat treat b th (1 th f. [56] References Cited 0 es ereo UNITED STATES PATENTS 10 Claims, 7 Drawing Figures 1,896,954 2/1933 Heap 68/D1G. 1 f

DEVICE FOR HEAT TREATMENT OF STRIPS AND THE LIKE The invention relates to a device for the heat treatment of strips, cords, ropes and the like.

Various difficulties arise in the heat treatment of strips, for example, during dyeing and in the case of strips of synthetic materials during heat-sealing. During dyeing with dispersion dyestuffs the fabric webs or strips are impregnated with the dyestuffs and then dried, and finally the dyestuffs are firmly bonded to the fabric fibers using heat, with the fabric being simultaneously heat-set. In the course of such a heat treatment it is easy for non-uniform warming to lead to a migration of dyestuff pigments, so that the finished product shows varying color concentration.

A further requirement which often occurs is that the strips to be treated, especially plastic strips, be kept under a tension which remains substantially constant within narrow limits. Uniformity in both warming and tension, and hence uniformity also in the finished product, may be achieved by warming with hot air, heat radiation or contact heat but the equipment necessary to achieve this uniformity is however bulky and inordinately large for its work rate.

When using the known roller cabinets the goods are subjected to more severe stretching and heating at each point at which it is in contact with the roller than over the free path between the rollers, so that any differences in tension which may have arisen during the weaving process are accentuated rather than smoothed out.

Such variations become particularly objectionable if it is desired, subsequently to shrink the goods. This is because in such a case, in spite of, or because of, the constant take-off of the goods, this tension has a vary-. ing effect on the intended uniformity of the shrinkage values.

Furthermore, if strips of differing color impregnation are passed through the heating chamber, there is the danger, that the pigments will diffuse from some of the impregnated goods that are introduced into the chamber and be deposited on goods impregnated with different colors which are subsequently passed'through the chamber thus causing undesirable blotching of colors and ruining the fabric. I

Disadvantages also result from use of devices where the goods are passed over heated rollers. In particular, in that case, the dyestuff pigments migrate to the side of the'strip exposed to the greatest heat; the strips are thus distorted and do not leave the device in the desired stretched form.

. The present invention therefore provides apparatus for the heat treatment of flexible strips comprising a vessel adapted to be filled with a heated fluid and having an open ended tube passing therethrough, said tube being located in said vessel such that the periphery of the tube over a major portion of the length thereof lies below the level to which the vessel is adapted to be filled and the ends are out of the fluid, said tube having at least one internal surface curved in the longitudinal direction of the tube.

The term strip" as used herein includes ropes, yarns, elongate sheets, cords, fabrics or like flexible elements.

Using this arrangement, a large amount of heat can be uniformly transferred onto the strip or strips to be treated over a relatively short path. For the treatment of strips, the curvature of the tubes is preferably uniaxial.

Local differences in heat, such as can arise when using radiant heat, are eliminated by employing a heating liquid having a large thermal capacity. Thus, it is possible to construct a compact heat treatment installation and to control the temperature to which the goods are subjected to within narrow limits. Differences in tension in the finished treated goods are thereby minimized and the risk of either migration or sublimation phenomena is substantially reduced.

Preferably, several tubes are provided which are so arranged, in conjunction with guide elements, that each strip to be treated is passed successively through several, and desirably through all, the tubes. Several tubes and the guide elements associated therewith can, in one embodiment of apparatus according to the invention, be so constructed and located that each of the two flat sides of a strip undergoing treatment passes through at least once in contact with one of the curved tube inner wall surfaces. Desirably strips passing through a plurality of tubes will spend varying periods in each tube through which they pass. This minimizes migration phenomena especially when the shorter dwell time precedes the longer dwell time in the process. The dwell times and the staggering or sequence of dwell times can be suited to the goods in question, but such variations are particularly useful in processing thick fabrics.

Using an apparatus according to the invention a strip, in particular a strip of thermoplastic material, can be passed through a heat treatment chamber under mechanical tension, thereby ensuring that no, or virtually no, shrinkage of the strip in its longitudinal direction occurs. In this embodiment the tube constitutes thechamber and the strip is passed over its surface which is progressively curved in one direction, the strip being in contact with the surface of the tube over the entire path, or almost the entire path, of the strip in this tube.

In the apparatus described above, the concave side of the tube is conveniently curved to conform substantially to the configuration adopted by a freely hung loop of the strip, and the tube ends project above the level of the liquid in the heating bath. The heating bath liquid preferably has a high specific heat. Depending on the temperature range required, possible bath liquids are water, glycerine, a salt melt or a metal alloy, for example, a eutectic alloy.

The mass of the heat transfer agent, that is the liquid of the bath is kept sufficiently high so that the accumulated heat is uniformly transferred to the fabric or strip passed through the tube. Because of the low heat loss to the surroundings other than the strip it is not necessary to supply much more energy than that absorbed by the strip itself passing through the device.

Means to control the temperature and circulation of the heat transfer agent can, and in general will, be located outside the vessel.

In order that the present invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawings in which:

FIG. 1 shows a side elevation in section through a simplified form of apparatus according to the invention;

FIG. 2 shows a section taken along the line 11-" of FIG. 1;

FIG. 3 shows a section corresponding to FIG. 1, through a second simplified embodiment of apparatus according to the invention;

FIG. 4 shows a section along the line IVIV of FIG.

FIG. 5 shows a section, similar to FIGS. 2 and 4, through a further embodiment of apparatus according to the invention;

FIG. 6 shows a section similar to that of FIGS. 1 and 3 through yet a further embodiment of apparatus according to the invention, and

FIG. 7 shows a still further embodiment of the invention.

In the device shown in FIG. 1, a channel 12, which is generally in the shape of a tube, passes through a heated vessel 10. The vessel 10 is filled as far as possible with a bath liquid 14 which is continuously circu lated, and kept at the temperature required for the treatment of the goods by means (not shown) located outside the vessel 10. While the detailed shape of the lower wall 16 and of the side walls 18 of the tube are not of great importance, the tube wall surface 20 is in the form of a portion of the surface of a cylinder. The ends of the tube terminate, in the illustrated embodiment, in the top wall of the vessel, but may equally project beyond the top wall of the vessel. They are of such shape and direction that a strip 22 to be introduced into the tube can be guided tangentially against the curved contact surface 20 if the strip is under tension, as shown.

In the arrangement according to FIGS. 3 and 4 a multiplicity of tubes 12.11, 12.12; 12.21, 12.22; 12.31, 12.32 are provided, which are arranged in an array, in the case shown two deep and four abreast. The tubes may, if so required, be coordinated in horizontal rows, for example, the tubes 12.11, 12.21, 21.31 may be positioned immediately above the tubes 12.12, 12.22, 12.32. Clearly other arrays are possible depending on output required and other considerations.

The curved tubes are preferably of rectangular cross section. The dimensions of the rectangle being dependent on the particular requirements.

In the arrangement according to FIG. 3, the curved surface against which the goods rest during passage is smaller in area in the case of the upper tube 12.11 of a pair than in the case of the lower tube 12.12 of that pair. If a strip 22 is passed in the direction of the arrows 24.26 through both tubes, that is to say, first through tube 12.11 and then through tube 12.12, a type of predrying takes place in tube 12.11, since the strip is not only warmed on the side which is in contact with the convex tube wall, but also as a result of the heat radiation emanating from the other tube walls. In tube 12.11, rapid pre-drying takes place which then is followed by a longer-lasting final drying in the longer tube 12.12.

The guide rollers and direction-changing rollers are so located that the strip 22 comes into contact tangentially with the convex upper inner wall surfaces of the tube. If the strip 22 is coming from a pre-drying chamber, the first roller, which introduces the strip into the warming device can also be located within the predrying device. Thus, depending on requirements, the rollers can be located inside or outside of the chambers in which they are exposed to an elevated or low temperature.

In FIG. 4, the superposed tubes which form a pair can be seen to be able to each receive one strip or several strips guided in parallel, so that with four pairs of tubes at least four continuously running lengths or strips can simultaneously be subjected to heat treatment. It is, however, also possible to choose a different sequence of treatments, for example, so that a strip is successively passed through the tubes in the following sequence: 12.11, 12.12, 12.21 and 12.22. Further, the sequence 12.11, 12.21 and 12.31 would also be possible. This latter sequence could be followed directly by the sequence 12.32, 12.22, 12.12 and from there to the outlet. Other combinations are also conceivable.

In the embodiment of FIG. 5 a plurality of tubular members are positioned in columns below each other, with each of the three tubular members 12.11, 12.12, 12.13; 12.21, 12.22, 12.23 arranged in two parallel vertically disposed columns. This construction can be employed equally well with tubes of differing lengths, in a similar manner such as that shown in FIG. 3, or with tubes of identical length in a similar manner to that shown in FIG. 6. FIG. 6 shows a different arrangement of tubes, in which the path to be covered by the goods in one tube is the same as the path in the other tube.

For the treatment of flat strips, the contact surface is curved only in one plane which is parallel to the longitudinal direction of the tube. For ropes or cords the surface may be of a different shape, for example, it may be provided with a groove for the rope, while still retaining the curvature of the tube in its longitudinal direction. It is desirable for the contact surface of the tube to be formed complementally to the exterior configuration of the goods. Furthermore, it is possible, according to the invention, to change the direction of curvature of the contact surface within a tube, that is to say, for example, one may use a corrugated tube with two contact surfaces having corrugations of large or small periodicity, so that the goods drawn therethrough come into contact alternately, within a single tube, with the two contact surfaces.

Using the apparatus of the present invention, thermoplastic strips of plastic can, while passing through the tube, be kept under enough tension to substantially reduce shrinkage of the strip in its longitudinal direction. The heating of the strip is brought about predominantly by conduction from the walls and radiation therefrom and only to a slight extent by convection.

In FIG. 7 the vessel 10 is provided with a plurality of tubes of the configuration shown in this cross-sectional view. It is to be particularly noted in this view that each of the sets of tubes have laterally extending corrugations 12.40 surrounded by the bath of liquid 14 and are so arranged that a single straight line path cannot be extended between adjacent ridges of the corrugations of one wall without intersecting a ridge of an opposed wall of an adjacent corrugation. This is believed to be quite clear from the view of FIG. 7 and attention therein is directed to numerals 30 and 40 which indicate the horizontal lines of the top and bottom walls, respectively, of the corrugated tubes.

Clearly it is possible within the scope of the invention to obtain numerous permutations and combinations of tubes and associated guides which are not described in detail hereinbefore depending on the material, quantity, shape strength and other variable features of the strip to be treated.

What is claimed is:

1. In an apparatus for heat treating indeterminate running lengths of fabric material to set the dye therein, comprising a vessel having top, bottom, side, and end walls filled with a heated fluid, spaced means defining entry and exit openings communicating with a tubular passageway that is surrounded by the heated fluid, said passageway including at least one curvilinear surface area for controlling the travel of said fabric and heating it as it passes through said tubular passageway.

2. In an apparatus as claimed in claim 1, wherein the vessel includes plural spaced means in the top wall defining entry and exit openings communicating with plural tubular passageways for travel of the fabric therethrough.

3. In an apparatus as claimed in claim 2, wherein one of said tubular passageways is of greater cross-sectional area than the other of said tubular passageways.

4. In an apparatus as claimed in claim 1, wherein the entry and exit openings are in the top wall of the vessel.

5. In an apparatus as claimed in claim 1, wherein the entry and exit openings are in the end walls of the vessel.

6. In an apparatus as claimed in claim 1, wherein the curvilinear surface area has a constant radius of curvature across its width at any given location along its length.

7. In an apparatus as claimed in claim 1, wherein said curvilinear surface is curved in only one direction.

8. In an apparatus as claimed in claim 2, wherein the running lengths of fabric are caused to traverse from one of said passageways to another of said passageways.

9. In an apparatus as claimed in claim 2, wherein the passageways are of varying length.

10. The method of heat treating indeterminate running lengths of fabric material comprising the steps of a. transporting said fabric having opposed surface areas through a bath of dye to apply a uniform coating thereto;

b. removing the excess dye from said fabric;

c. traversing it in a first direction over a curved surface of a passageway in a heated receptacle to set the dye in one of said surface areas, and

d. reversing the travel of the fabric through another passageway to set the dye in another of said surface areas. 

2. In an apparatus as claimed in claim 1, wherein the vessel includes plural spaced means in the top wall defining entry and exit openings communicating with plural tubular passageways for travel of the fabric therethrough.
 3. In an apparatus as claimed in claim 2, wherein one of said tubular passageways is of greater cross-sectional area than the other of said tubular passageways.
 4. In an apparatus as claimed in claim 1, wherein the entry and exit openings are in the top wall of the vessel.
 5. In an apparatus as claimed in claim 1, wherein the entry and exit openings are in the end walls of the vessel.
 6. In an apparatus as claimed in claim 1, wherein the curvilinear surface area has a constant radius of curvature across its width at any given location along its lengtH.
 7. In an apparatus as claimed in claim 1, wherein said curvilinear surface is curved in only one direction.
 8. In an apparatus as claimed in claim 2, wherein the running lengths of fabric are caused to traverse from one of said passageways to another of said passageways.
 9. In an apparatus as claimed in claim 2, wherein the passageways are of varying length.
 10. The method of heat treating indeterminate running lengths of fabric material comprising the steps of a. transporting said fabric having opposed surface areas through a bath of dye to apply a uniform coating thereto; b. removing the excess dye from said fabric; c. traversing it in a first direction over a curved surface of a passageway in a heated receptacle to set the dye in one of said surface areas, and d. reversing the travel of the fabric through another passageway to set the dye in another of said surface areas. 